Acute non-lymphoblastic leukemia (ANLL) is a form of malignancy generally seen in adult populations. Approximately 17% of all leukemia cases in children under 15 years of age are classified as ANLL with a reported annual incidence rate per million population of 6.2 for whites and 4.5 for non-whites. The Childrens Cancer Study Group (CCSG) has recently completed an analytic study designed to assess specific environmental exposures as potential risk factors for ANLL in children. This study, which included 204 case-control pairs, identified statistically significant risks to be independently associated with parental occupational pesticide exposures, postnatal household pesticide exposure to the index child, paternal occupational petroleum product exposure, and maternal marijuana use during the index pregnancy. Of interest, several of these factors demonstrated a stronger association within specific age and morphologic subgroups. The findings from this study provide the direction for the proposed epidemiologic investigation of childhood ANLL. The proposed study will include approximately 630 cases of ANLL in person diagnosed prior to 18 years of age. The primary objectives of the study are to: (i) confirm the association of pesticide exposure and ANLL risk and to identify the substances or class of pesticides responsible for the association; (ii) confirm the association of solvents and petroleum products and ANLL risk and determine the class of solvent responsible; (iii) confirm the association of maternal marijuana use and ANLL risk; and (iv) identify subgroups, defined by age at diagnosis, FAB morphology, cytogenetic abnormality, or clinical features of the leukemia, in which the associations with pesticide, solvent, or marijuana exposure are strongest. Cases will be ascertained through the member institutions of the Childrens Cancer Study Group. Cases of ANLL, diagnosed during a 48 month period, will be compared to a series of age-, sex-, and race-matched regional controls selected using random digit dialing. Parents of cases and controls will be interviewed by telephone. The study will have a sufficient sample size within most of the morphologic subgroups of ANLL (FAB morphology classification: MI- M7) to provide sufficient power for assessing the study hypotheses. Classification of cases according to FAB morphology and cytogenetics will be made by centralized review.